Wednesday, September 1, 2010

Terminal Ballistics and Hunting; Redux

Terminal Ballistics and Your Hunting(Or, why I like big bores so much.)

Weatherby Eurosport in 30/06,
my light rifle.

One of those things that I’ve never understood is how someone could spend hundreds of dollars on a rifle, spend the same and sometimes more on a scope, and then pick up a box of the least expensive ammunition they can find. Not that there is anything intrinsically wrong with such an approach, but when a hunt can cost you thousands of dollars in incidental costs, what’s twenty more dollars?

With that in mind I thought I would discuss terminal performance.

What a bullet should do:

There are two ways that a bullet works, either by punching a hole through a vital zone or disintegrating inside and destroying the same. The fact is that given sufficient disruption of a primary system, death will occur, therefore a projectile works by stopping or damaging a vital life support system and causing death by suffocation, shock, or central nervous system shut down.

A bullet should reach its target unerringly, penetrate and do what is desired of it. Varmint hunting prefer to have the projectile blow up inside the target and expend its energy within. Medium and big game hunters vary in their desire for controlled expansion. Bullets shouldn’t be expected to do everything regardless of circumstances. At close range some bullets just won't hold up. At long ranges some won't do what they're designed to do.

For handloaders, there is one bullet that qualifies for the do-all-to-end-all. (In my opinion anyway!) That would have to be the big-bore hardcast LBT style bullets. Close range to long range they make a big hole and keep on going. Just ask the buffalo runners of yesterday. But we will get to that shortly.

Today the trend is towards deep penetration and retained weight. Originally, the Nosler Partitions, and now the Swift A-Frames, and the Failsafes are the yardstick by which all other bullets are measured. I will get to solids shortly. Since I am predominantly a hog hunter, I can speak with some confidence as to what works and what doesn’t. If we limit our discussion to larger pigs of 225 lbs or more, the need for quality bullets becomes apparent. I have observed that at about 150 lbs hogs start to develop the shield and by the time they are about 225 the shield is now a hardened gristle deposit.

Imagine, if you will, a hollow-pointed bullet hitting that. The expanding bullet drives into this dense, inelastic material. The bullet expands rapidly in this material and loses velocity. At some point it starts to shed pieces and loses mass. Without additional mass driving it from behind, penetration slows dramatically. In all probability it never penetrates past the gristle layer. What you get is a surface wound, little to no blood trail, and no hog.

160gr Soft Points

The reason the 30/30 has taken so much game, is that it throws a 150gr softpoint at a moderate velocity. It hits, expands, and the long bullet shank goes on its merry way. If you shot the same bullet out of a 30-06, at the same ranges as a 30/30, it might not hold together. Too much speed and not enough jacket strength. So it is also important to match the projectile to the cartridge parameters.

A non-partition softpoint doesn’t expand, as much as it is disrupted by the initial impact. In this case, mass directly determines penetration. The heavier the softpoint, the more likely it will penetrate deeper. The original Barnes made its money with its softpoint line. Heavy for caliber bullets (How about 600gr 458s and 250gr 308s!), driven at moderate speed disrupted well, retained 80% of their weight and drove deep. The only problem the Barnes Soft Points ever suffered from was over-expansion and the commensurate deceleration, which limited penetration, and on very large game sometimes the softpoints failed to smash through bones.

XP3 Bullets

Now if you will, try the same scenarios with a Failsafe or XP3. The momentum afforded by the encased base allows the bullet to continue through the gristle and bone, and drive into the vitals.

Solids work by penetrating deeply and displacing tissue. Certain designs are meant primarily to drive through bones or large masses of flesh and muscle, like the Woodleigh Sledge Hammer, Barnes homogenous, and the AGS by Speer, which I understand is the best solid commercially available. These bullets are designed to drive deep, drive straight, and smash their way through anything intervening. In the hands of an excellent shot, a solid will reach the target it is intended to. “Karamojo “ Bell used solids almost exclusively in his .265 and .275 for all the game he took, dangerous or otherwise.

The latest take on solids, is the LBT style hardcast lead bullets. They are heat treated to make them tougher than they would otherwise be. They penetrate deeply, creating massive wound channels. They are accurate within their own parameters, and are available in number of calibers from 30 to .510. I use them in my 45LC and 458WM.

It has always been my preference to lean in the direction of greater penetration. Since I’ve always been suspect of my abilities, and hope to never lose an animal, I plan for the worse, and only take shots that I am certain of.

Shock:

The Weatherby line up.

In the late fifties and early sixties Roy Weatherby thought that if he could push bullets fast enough, the “hydrostatic shock” of the projectile moving through the muscles and tissues of an animal would be sufficient to cause instantaneous death. Two things worked against Roy’s theory. One, bullets at that time could not withstand the then phenomenal speeds at which the Weatherby rifles/cartridges shot them. Secondly, hydrostatic shock doesn’t work on large elastic masses. On the minimal mass of a prairie dog, it will, on hippos, no. It has been conclusively proven that bullet placement, not energy, is what kills. In the end it is the hunter’s ability to accurately place a bullet in the right spot that determines whether he is successful or not.

Stopping Power:

Image Credit: Jobe Roco

Classic, Old School Stopping Power!

Stopping power is directly related to the caliber.

Stopping power is directly related to the caliber.

There, I’ve said it twice. In other words, the bigger it is the more likely it will settle hash right then and there. As long as it has enough velocity to penetrate and all other things being equal, the larger the cross section, the more powerful the knock down capability. Empirical evidence suggests that weight, velocity, and the cross section of a bullet, determines its ability to knock down, that is to stun or immediately kill an animal. Pondoro Taylor and Hatcher both devised formulae and tables to estimate the knockdown power of any given projectile. They both weigh in heavily in favor of the bigger bores.

If you peruse the cartridge tables, you will notice two things, one, the big bore cartridges are slow, and two the projectile weights are high. When velocity is low you need mass and frontal area. Again empirical evidence suggests that when you are confronted with a mad Brownie, a 45-70 is better than say a 338WM. Otherwise why would so many Alaskan bush pilots prefer the Guide Gun and the Alaskans? The answer is the ability of a slightly souped up 405gr, .458cal solid bullet being able to traverse, end for end, an 800lb bear, smashing everything in its way. Wound channels are commensurately large in proportion with frontal cross section. As caliber goes up, the area goes up exponentially. A 30caliber bullet has a frontal area of .074 square inch versus .165 sq in for a .458, more than twice the area.

You can never be certain as to what conditions will be when you have to put a bullet into the vital zone. The ability of the projectile to penetrate through any intervening meat, bone or viscera, into the vital zone is directly related to construction and design. Range and impact velocity also are variables to contend with. The lines are blurring slightly when one has to choose between a light quick bullet and a heavier slower one. Due to the better qualities of the newer bullets, it has become easier to drop in weight, add velocity and be confident of retained terminal weight. The 30-06 loaded with 150gr Failsafes shoots as flat as a Remington 7mm Magnum and will retain almost all of its weight. But retained momentum and energy are diminished substantially as the bullet weight goes down.

How should you decide? I am convinced that 90% of all game is taken inside of 100 meters. In the end all that matters is whether a bullet penetrated and did sufficient damage to kill quickly. If I was hunting Florida whitetails exclusively, and limited my shot to reasonable ones, I wouldn’t hesitate to use any of the commercial soft points. I would only choose the brand that gave me the best accuracy. Florida deer are small, and considering I do most of my non-hog shooting with a 30-06, there is no real need for a deep penetration. That’s a personal preference; at the ranges I am capable of shooting to, you could cut the end of the bullet off with bolt-cutters, and it would still hit the target close enough to point of aim. But if I were going to Africa (plains game), or to Arizona for elk, even white tails in Texas, I would use nothing less than Winchester Failsafe/XP3 or Remington Swift A-Frames. I would limit myself to shots inside of 150 yards, where I could be absolutely sure of where my bullets hit. I would familiarize myself with the game animal until I could visually dissect it and know where every vital organ lies. I’ve killed enough pigs to be almost certain of every shot’s terminal trajectory on them. “Karamojo" Bell did this with much success when meat shooting North American game in Alaska, and then in Africa where he made his fame shooting elephants for ivory. But even though I can visualize where the pig’s heart, spine, and liver lay, occasionally I am still surprised. Years ago, I took a shot at a small hog, aiming for the box made by the eyes and ears. Imagine my surprise when I recovered him and found that instead of a frontal head shot, I had made a side brain shot.

450gr LBT's

If you are picking your shots, and not picking fights or trying to stop them quickly, then it is reasonable to use any cartridge and rifle combination that is suitable for the game at hand. For instance, I think I am a reasonably capable shot with my Weatherby 30-06. Anything inside of a couple of inches is in eminent danger of being ventilated at 150 meters or less. With that in mind, I would not hesitate to use it with 180gr A-Frames against brown bears, and here is the operative phrase, if I had to. But I think I would feel better with my 458WM. At 100 meters I can keep all my shots within 3 inches. 450gr hard cast LBT type bullets at 1800fps, will double lung any grizzly, bust both shoulders, or traverse the grizzly end for end.

And If things somehow got ugly and I have to end a fight, I’ll be confident that between the 458 and I, we can swat one down flatter than a stray aluminum can on the expressway.

Your excellent post resonates well with my experiences. I started out as a fast skinny bullet guy. After witnessing the performance of big and slow bullets on game I became a convert.

Put a big bullet where it goes and you'll make meat reliably. Straight through penetration, large permanent wound channel and two holes = fast bleed out and little or no tracking required. Can't say that with deer and bear I've tracked that were hit with the skinny bullets that didn't exit and the wound channels clogged with the "gut soup" caused by the shock of the impact, which made it a grid search instead of a blood trail.

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